According to the World Health Organization, approximately 150 million people worldwide have diabetes mellitus. The two principle forms of diabetes are type 1 diabetes, in which the pancreas fails to produce insulin, and type 2 diabetes, in which the body fails to respond properly to the insulin produced (insulin resistance). Accounting for about 90% of all diabetes cases, type 2 diabetes is by far the most common. In both types of diabetes, the absence of insulin action or proper response to insulin results in elevated levels of serum glucose (hyperglycemia). Serious complications associated with diabetes include retinopathy (leading to visual impairment or blindness), cardiovascular disease, nephropathy, neuropathy, ulcers and diabetic foot disease.
Individuals with type 1 diabetes currently require insulin therapy. While in many cases type 2 diabetes can be managed with diet and exercise, drug intervention also frequently is required. Besides insulin, which is needed by about one-third of patients with type 2 diabetes, current antidiabetic therapies include biguanides (which decrease glucose production in the liver and increase sensitivity to insulin), sulfonylureas and meglitinides (which stimulate insulin production), alpha-glucosidase inhibitors (which slow starch absorption and glucose production), and thiazolidinediones (which increase insulin sensitivity). These medicines are often used in combination, and even then may not provide adequate glycemic control or may produce undesired side effects. Such side effects include lactic acidosis (biguanides), hypoglycemia (sulfonylureas), and edema and weight gain (thiazolidinediones). Therefore, new antidiabetic agents providing improved glycemic control and lacking these adverse effects are highly desired.
One promising target for therapeutic intervention in diabetes and related disorders is the glucose transport system of the kidneys. Cellular glucose transport is conducted by either facilitative (“passive”) glucose transporters (GLUTs) or sodium-dependent (“active”) glucose cotransporters (SGLTs). SGLT1 is found predominantly in the intestinal brush border, while SGLT2 is localized in the renal proximal tubule and is reportedly responsible for the majority of glucose reuptake by the kidneys. Recent studies suggest that inhibition of renal SGLT may be a useful approach to treating hyperglycemia by increasing the amount of glucose excreted in the urine (Arakawa K, et al., Br J Pharmacol 132:578-86, 2001; Oku A, et al., Diabetes 48:1794-1800, 1999). The potential of this therapeutic approach is further supported by recent findings that mutations in the SGLT2 gene occur in cases of familial renal glucosuria, an apparently benign syndrome characterized by urinary glucose excretion in the presence of normal serum glucose levels and the absence of general renal dysfunction or other disease (Santer R, et al., J Am Soc Nephrol 14:2873-82, 2003). Therefore, compounds which inhibit SGLT, particularly SGLT2, are promising candidates for use as antidiabetic drugs. Compounds previously described as useful for inhibiting SGLT include spiroketal-glycoside derivatives (described in WO2006080421), C-glycoside derivatives (such as those described in U.S. Pat. No. 6,414,126, US20050209166, US20050233988, WO2005085237, U.S. Pat. No. 7,094,763, US20060122126 and WO2006108842), O-glycoside derivatives (such as those described in U.S. Pat. No. 6,683,056, US20050187168, US20060166899, US20060234954 and US20060247179), cyclohexane derivatives (such as those described in WO2006011469), and thio-glucopyranoside derivatives (such as those described in US20050209309 and WO2006073197).